SBC Lynx is extremely flexible in terms of hardware configurations. This document describes main options related to booting. In case you need a configuration that is not listed here, please contact Sales department.

Available options

By default, eFUSE bits are not supported as bootstrap option [1]. Thus two actual modes can be selected by S12.1 and S12.2 switches, as listed in the following table.

BOOT_MODE[1:0]

Boot type

S12.2 (BOOT_MODE1)

S12.1 (BOOT_MODE0)

Notes

00

Boot from eFUSEs

off

off

Supported on request only

01

Serial downloader

off

on

10

Internal boot

on

off

Default

11

reserved

on

on

Reserved

[1] Nevertheless, SBC Lynx can support this option. This is a clear example of a feature that can be implemented on request. For more information please contact Sales department.

Internal boot

When Internal boot mode is selected, GPIO override technique is used to configure bootstrap flags, also known as BOOT_CFG bits. This means that 24 processor's signals - specifically LCD1_DATA[23:00] - are latched by iMX6UL processor upon reset to get bootstrap flags. As such, these signals need to be pulled up or down to select the proper configuration.

The following table summarizes these configurations. Pull-up/down resistors are 10kOhm.

Ordering code(s) →-----BOOT_CFG bits↓

XUBx0xxxXUBx2xxx

XUBx1xxx

LCD_DATA23 (BOOT_CFG4_7)

pull-down

TBD

LCD_DATA22 (BOOT_CFG4_6)

pull-down

TBD

LCD_DATA21 (BOOT_CFG4_5)

pull-down

TBD

LCD_DATA20 (BOOT_CFG4_4)

pull-down

TBD

LCD_DATA19 (BOOT_CFG4_3)

pull-up

TBD

LCD_DATA18 (BOOT_CFG4_2)

pull-down

TBD

LCD_DATA17 (BOOT_CFG4_1)

pull-down

TBD

LCD_DATA16 (BOOT_CFG4_0)

pull-down

TBD

LCD_DATA15 (BOOT_CFG2_7)

pull-up

TBD

LCD_DATA14 (BOOT_CFG2_6)

pull-up

TBD

LCD_DATA13 (BOOT_CFG2_5)

pull-up

TBD

LCD_DATA12 (BOOT_CFG2_4)

pull-up

TBD

LCD_DATA11 (BOOT_CFG2_3)

pull-up

TBD

LCD_DATA10 (BOOT_CFG2_2)

pull-down

TBD

LCD_DATA09 (BOOT_CFG2_1)

pull-up

TBD

LCD_DATA08 (BOOT_CFG2_0)

pull-up

TBD

LCD_DATA07 (BOOT_CFG1_7)

pull-down

TBD

LCD_DATA06 (BOOT_CFG1_6)

pull-down

TBD

LCD_DATA05 (BOOT_CFG1_5)

pull-up

TBD

LCD_DATA04 (BOOT_CFG1_4)

pull-up

TBD

LCD_DATA03 (BOOT_CFG1_3)

pull-up

TBD

LCD_DATA02 (BOOT_CFG1_2)

pull-up

TBD

LCD_DATA01 (BOOT_CFG1_1)

pull-up

TBD

LCD_DATA00 (BOOT_CFG1_0)

pull-up

TBD

The following sections provides additional notes related to the use of Internal boot on SBC Lynx.

Ordering codes XUBx0000

Boot flow of ordering codes XUBx0000

Serial downloader

Generally speaking, serial downloader allows to download a program image to the target over USB or UART connections. The following flow chart details the sequence of operations that are performed by BootROM in Serial Download mode (source Applications Processor Reference Manual[1].

Serial download boot flow

In case Manufacture mode is enabled, before probing UART and USB interfaces, BootROM tries to boot from SDHC1 interface if any device is connected to it.

The following sections provides additional notes related to the use of Serial Downloader on SBC Lynx in order to warn the user about possible conflicts that may occur depending on what is connected to USBOTG1 port, UART1 and UART2 interfaces.

Ordering codes XUBx0000

UART1: this UART is routed to connector J42 that is typically used for console.

UART2: this UART is routed to connector J46 that is dedicated to optional DWM WiFi/Bluetooth module. Even if DWM is populated, no electrical conflicts occur.

USBOTG1: this interface is connected to J55. The use of this port is user defined.